The human gastrointestinal microbiome has been linked to metabolic disease and obesity; however, the relationship between host genetic variation and the diversity of gut microbiomes is largely unknown. Modification of the microbiome for therapeutic applications has the potential to treat a variety of disorders (Xu M Q et al., World J. Gastroenterol. 21:102-111(2015)). The enormous market for foods and supplements containing probiotic bacteria underscores the increasing public awareness of treatments involving introduction of beneficial bacteria to the gastrointestinal system.
Studies in humans and in animal models have shown that obesity is associated with a shift in the proportions of bacterial communities in the gut. Administration of the microbiota of obese individuals into the stomach of germ-free mice leads to greater weight gain in the recipient mice than in germ-free mice receiving microbiota from lean individuals, suggesting that microbial communities can predispose a host to weight gain or weight loss (Ley R E, Curr. Opin. Gastroenterol. 26:5-11(2010)). However, identification of bacteria associated with an obese or lean phenotype varies between studies. Understanding the interactions between a human host and the microbiome can lead to new treatments for a range of medical conditions by modifying the gut microbiome of a subject.